Indoor Air Quality Measurement Onboard Royal Malaysian Navy Warship: Implication for Crew Stress Level

Indoor Air Quality (IAQ) is a critical determinant of health, operational performance, and psychological well-being, particularly in enclosed and high-risk maritime environments such as warships. This study examines IAQ conditions onboard KD JEBAT, a Royal Malaysian Navy frigate, and their implications for crew stress levels. Five IAQ parameters, carbon dioxide (CO₂), carbon monoxide (CO), relative humidity, temperature, and air movement were systematically monitored using a calibrated IAQ multifunction data logger across four mission-critical compartments: the Galley, Combat Information Center (CIC), Bridge, and Machinery Control System Room (MCSR). Data were collected over an 8-hour surrogate duration, segmented into four operational time slots, and benchmarked against the Industry Code of Practice on Indoor Air Quality (ICOP 2010). Measurements were further contextualized against crew occupancy patterns, task intensity, and compartment functions. Finding of IAQ assessments revealed CO₂ exceedances in CIC and MCSR, low wind speeds in all compartments, and thermal discomfort across sections highlighting stress related conditions to ventilation and temperature imbalances. These environmental stressors were closely associated with cognitive fatigue, physiological strain, and reduced situational awareness. The study underscores the importance of continuous IAQ monitoring, demand-responsive ventilation, and human-centered engineering strategies to mitigate occupational stress. The outcomes offer practical and policy-level insights aligned with Environmental, Social, and Governance (ESG) principles, the United Nations Sustainable Development Goals (SDGs), and Malaysia MADANI priorities for defense infrastructure.